Monoazo dyestuffs



Patented Mar. 3 1, 1953 MONOAZO DYESTUFFS Werner Kuster, Basel, Switzerland, assignor to J. R. Geigy A. G., Basel, Switzerland, a Swiss N Drawing. Application May 18, 1951, Serial N0. 227,120. In Switzerland June 9, 1950 6 Claims. 1

The present invention is concerned with the production of chromable monoazo dyestuffs which are distinguished by their dyeings on wool obtained according to the single chroming bath method and which give fast red dyeings.

The single bath chroming method is very popular in the fast dyeing of wool because of the single process compared with the afterchroming method and because the shade developed on the goods can be judged at once which is of great advantage to the dyer when shading. Dyestufls which are suitable for dyeing wool in a single chroming process, the dyebath containing ammonium salts such as ammonium sulphate and alkali chromates such as sodium chromate are also, therefore, in great demand because those dyestuffs which can be afterchromed are only exceptionally suitable for chroming in the single bath process. A chrom dyestuff for use in the single bath process must be sufficiently water soluble to prevent it being precipitated by the developing salts; it must not reduce the chromates and should not form any complex chromium compounds in the dye liquor which can either be precipitated undissolved or not draw onto the fibres. It must also have a good aiiinity for wool in a neutral to weakly acid bath in order that the bath may be as fully exhausted and the shade as fully developed as possible. The best criterion for the suitability of a dyestuff for the one bath method is the complete exhaustion of the dye liquor which contains no acid within the usual dyeing time and the development of the full depth of shade which would have been attained by afterchroming the dyeing. The monoazo dyestuffs according to this invention completely fulfill the conditions required for the single bath chroming method and produce very beautiful full and fast wool dyeings leaving a completely exhausted" dyebath within the usual dyeing time.

The dyestufls according to this invention are obtained in the form of dark alkali salts by coupling the diazotised 6-nitro-4-alkylor 4-cycloalkyl-Z-aminophenols which have an aliphatic or alicyclic hydrocarbon radical of 5-8 carbon atoms in the 4-position of the diazo component with 1- such as sodium pyrophosphate or other dispersing agents for dyeing wool according to the single bath process.

The new dyestufis according to this invention are superior with regard to their suitability for the single bath process to the known similar dyestuffs the coupling components of which contain sulphonic acid groups or two carboxyl groups.

The following examples illustrate the invention without limiting it in any way. Where not 0therwise stated, parts are given by weight and temperatures are in degrees centigrade. The rela tionship of parts by Weight to parts by volume is that of kilogrammes to litres.

Example 1 23.6 parts of 6nitro4-cyclohexyl-2-aminophenol are dissolved with 4.1 parts of 100% caustic soda lye in 200 parts of Water and, with a solution of 6.9 parts of sodium nitrite in 35 parts of water, are added dropwise to a mixture of 25 parts of concentrated hydrochloric acid and 100 parts of water at 0-3", whereupon the diazo compound is formed as a thick greenish yellow suspension. After the nitrite reaction has disappeared, the acidity of the diazo suspension is made neutral to Congo paper with some sodium bicarbonate, after which a solution of 24 parts of 1-(3-chlorophenyl)-5-pyrazolone'-'3-carboxylic acid and 8.1 parts of 100% caustic soda lye in 200 parts of water are added. Sufiicient concentrated aqueous ammonia is then added dropwise within half an hour to give the coupling mixture a weak phenolphthalein alkaline reaction whereupon it is stirred at a very slowly rising temperature until the coupling is completed. The temperature should not rise higher than 20. The dyestufi is then filtered oiT, washed with 2 sodium chloride solution and dried. It forms a dark black-violet powder which only slightly dissolves in water and completely dissolves in concentrated sulphuric acid. In water it gives a reddish-violet colour and'in sulphuric acid a bluish red colour. It is advantageous to mix the dyestuii with 10% of its own weight of sodium carbonate and a dispersing agent before it is put to a practical use. It dyes wool in a yellow-orange shade from an acid bath which changes to a bluish-red on chroming. Dyeings of the same shade are obtained with the single bath process when the bath contains little or no acid. In this process, the bath is also fully exhausted. The dyeings obtained "both by the afterchroming method and the single bath process have very good light and wet fastness properties.

Example 2 22.4 parts of G-nitro--tertiary amyl-2-aminophenol and 4.1 parts of 100% caustic soda lye are dissolved in 200 parts of water and are poured with a solution of 6.9 parts of sodium nitrite in 35 parts of water into a solution of 25 parts of concentrated hydrochloric acid and 100 parts of water, whereupon the yellow coloured diazo compound forms a thick suspension. The acidity of the diazo suspension is made neutral to Congo paper by the addition of sodium bicarbonate after diazotisation is completed, after which a solution of 24 parts of 1-(3'-chlorophenyl)-5- pyrazolone-3-carboxylic acid and 8.1 parts of 100% caustic soda lye in 200 parts of water are added. Finally, parts of concentrated aqueous ammonia are added to the coupling mixture so that it has a slight phenolphthalein alkaline reaction and the temperature is slowly raised from 3 to 20. On completion or the coupling, the difiicultly soluble dyestuff is filtered ofi. washed with 2 /270 sodium chloride solution and dried. It is then advantageous to reduce it with sodium pyrophosphate and a dispersing agent.

The dyestufi is a dark violet powder which dissolves in water with a reddish-violet and in conc. sulphuric acid with a yellowish-red colour. From an acid bath, it dyes wool in a brownishyellow shade, which on afterchroming changes to a bluish-red.

The great advantage of the product is that wool dyeings of the same shade and strength are also produced with the single bath chroming process while completely exhausting the bath which contains little or no acid as with the afterchroming process.

A similar dyestuff is obtained if 26.6 parts of 6-nitro-4-0ctyl-2-aminophenol are used instead of 22.4 parts of G-nitro-d-tertiary amyl-2-arninophenol in the above example.

Example 3 22/: parts of 6-nitro-2-amino-4-tert. amyl phenol and 4.1 parts of sodium hydroxide are dissolved in 200 parts of water and, together with a solution of 6.9 parts of sodium nitrite in 35 parts of water, are added dropwise to a mixture of 25 parts by volume of cone. hydrochloric acid and 100 parts of water at a temperature not exceeding 3.

The diazo compound forms a yellow coloured suspension. On completion of the diazotisation, the acidity of the diazo suspension is neutraiised by the addition of a little sodium bicarbonate.

Asolution of 27.6 parts of 1(3.4=-dichloror phenyl)-5-pyrazolone-3-carboxylic acid and 8.1 parts of sodium hydroxide in 200 parts of water is then added. Finally, the reaction mixture is made weakly phenolphthalein alkaline by the addition of a sodium carbonate solution. The mixture is stirred overnight and then the temperature is raised from 3 to The dyestuii which is precipitated, is filtered off, washed with a 2 92; common salt solution and dried.

The product is a black-violet powder which dissolves in hot water with, a red-violet and in cone. sulphuric acid with a red-orange colour. For practical use it is advantageous to grind the powder well with a little sodium carbonate and a dispersing agent. From an acid bath, the dyestufi dyes wool in a red-orange shade-which changes into a bluish-red shade on aiterchroming. Dyeings of equal shade and strength with very good wet and light fastnesses are obtained by the single bath chroming method either with .4 or without a slight addition of acid. The bath is completely exhausted.

A very similar dyestuii is obtained if, in the above example, the 22.4 parts of 6-nitro-2- amino-e-tert. amyl phenol are replaced by an equivalent amount, namely 26.6 parts of G-nitro- 2-amino-4-cyclohexyl phenol.

Example 4 22.4 parts of 6-nitro-2-amino-4-tert. amyl phenol and 4.1 parts of sodium hydroxide are dissolved in 200 parts of water and added dropwise, with a solution of 5.9 parts of sodium nitrite in 35 parts of water, to a mixture of 25 parts by volume of cone. hydrochloric acid and parts of water at a temperature of 0-3.

On completion of the diazotisation, the yellow suspension is neutralised with a little sodium bicarbonate until it gives a neutral reaction to Congo red and then a solution of 27.6 parts of l (3.6 dichlorophenyl) 5 pyrazolone-B- carboxylic acid and 8.1 parts of sodium hydroxide in 200 parts of water is added. Finally, the reaction mixture is made slightly phenolphthalein alkaline by the addition of a 15% sodium carbonate solution. It is stirred overnight at a temperature gradually rising to 20. The dyestufi which precipitates is filtered off, washed with a 2 /2); common salt solution and dried.

The dyestufi is a dark brownviolet powder. It dissolves in hot water with a red-violet and in conc. sulphuric acid with a brownish-yellow colour. For practical use it is advantageous to grind the powder well with a little sodium carbonate and a dispersing agent. From an acid bath, the dyestuff dyes wool in a red-orange shade which changes into a bluish-red shade on afterchroming. Dyeings of equal shade and strength with very good wet and light fastnesses are obtained by the single bath chroming method either with or without a slight addition of acid. The bath is completely exhausted.

A very similar dyestufi is obtained if, in the above example, the 22.4 parts of 6-nitro-2- aminoi-tert. amyl phenol are replaced by an equivalent amount, namely 26.6 parts of 6-nitro- 2-amino-4-octyl phenol.

Example 5 0.2 part of the dyestui'l obtained according to Example 1 are added to a solution of 1 part of dehydrated sodium sulphate, 0.2 part of sodium monochromate and 0.3 part of ammonium sulphate in 400 parts of water. 10 parts of wool are then entered at 50. The bath is brought to the boil within one hour and held at the boil for another hour to fully develop the shade. The wool which is dyed a bluish-red colour is then rinsed and dried. I

What I claim is:

1. A monoazo dyestuff having the general formula:

oiN N=NOH-C-OOOH N l l R A wherein R represents a member selected from the group consisting of aliphatic and alicyclic hydrocarbon radicals with 5-8 carbon atoms, and A represents a member selected from the group consisting of 3-ch1orophenyl, 3.4-dichlorophenyl and 3.6-dichloropheny1 radicals.

5 6 2. A monoazo dyestufi having the :tormula: 5. A monoazo dyestufi having the formula:

OH OH om- -N=NOH-O-OOOH 01N- N=N--CHfii-COOH 1L: 5 o /N N HaC--CH; HaC-+OH 3. A monoazo dyestufi having the formula: 01

OH 6. A monoazo dyestufi having the formula:

OH oQN- N=NCH-C-COOH I Q l OzN N=NCH-C-COOH N o N F/ CFCH: HaC-CH3 01 Ha Ha Cl 2H5 o 01 4. A monoazo dyestufi having the formula: WERNER KUSTER.

0H REFERENCES CITED The following references are of record in the o N file of this patent: UNITED STATES PATENTS I Number Name Date HaO-(f-CHE 2,464,322 Krebser et a1 Mar. 15, 1949 H O E C1 FOREIGN PATENTS a a Number Country Date 0H3 189,049 Switzerland May 1, 1937 

2. A MONOAZO DYESTUFF HAVING THE FORMULA: 